sys/kern/sys_pipe.c

   1 /*-
   2  * SPDX-License-Identifier: BSD-4-Clause
   3  *
   4  * Copyright (c) 1996 John S. Dyson
   5  * Copyright (c) 2012 Giovanni Trematerra
   6  * All rights reserved.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice immediately at the beginning of the file, without modification,
  13  *    this list of conditions, and the following disclaimer.
  14  * 2. Redistributions in binary form must reproduce the above copyright
  15  *    notice, this list of conditions and the following disclaimer in the
  16  *    documentation and/or other materials provided with the distribution.
  17  * 3. Absolutely no warranty of function or purpose is made by the author
  18  *    John S. Dyson.
  19  * 4. Modifications may be freely made to this file if the above conditions
  20  *    are met.
  21  */
  22
  23 /*
  24  * This file contains a high-performance replacement for the socket-based
  25  * pipes scheme originally used in FreeBSD/4.4Lite.  It does not support
  26  * all features of sockets, but does do everything that pipes normally
  27  * do.
  28  */
  29
  30 /*
  31  * This code has two modes of operation, a small write mode and a large
  32  * write mode.  The small write mode acts like conventional pipes with
  33  * a kernel buffer.  If the buffer is less than PIPE_MINDIRECT, then the
  34  * "normal" pipe buffering is done.  If the buffer is between PIPE_MINDIRECT
  35  * and PIPE_SIZE in size, the sending process pins the underlying pages in
  36  * memory, and the receiving process copies directly from these pinned pages
  37  * in the sending process.
  38  *
  39  * If the sending process receives a signal, it is possible that it will
  40  * go away, and certainly its address space can change, because control
  41  * is returned back to the user-mode side.  In that case, the pipe code
  42  * arranges to copy the buffer supplied by the user process, to a pageable
  43  * kernel buffer, and the receiving process will grab the data from the
  44  * pageable kernel buffer.  Since signals don't happen all that often,
  45  * the copy operation is normally eliminated.
  46  *
  47  * The constant PIPE_MINDIRECT is chosen to make sure that buffering will
  48  * happen for small transfers so that the system will not spend all of
  49  * its time context switching.
  50  *
  51  * In order to limit the resource use of pipes, two sysctls exist:
  52  *
  53  * kern.ipc.maxpipekva - This is a hard limit on the amount of pageable
  54  * address space available to us in pipe_map. This value is normally
  55  * autotuned, but may also be loader tuned.
  56  *
  57  * kern.ipc.pipekva - This read-only sysctl tracks the current amount of
  58  * memory in use by pipes.
  59  *
  60  * Based on how large pipekva is relative to maxpipekva, the following
  61  * will happen:
  62  *
  63  * 0% - 50%:
  64  *     New pipes are given 16K of memory backing, pipes may dynamically
  65  *     grow to as large as 64K where needed.
  66  * 50% - 75%:
  67  *     New pipes are given 4K (or PAGE_SIZE) of memory backing,
  68  *     existing pipes may NOT grow.
  69  * 75% - 100%:
  70  *     New pipes are given 4K (or PAGE_SIZE) of memory backing,
  71  *     existing pipes will be shrunk down to 4K whenever possible.
  72  *
  73  * Resizing may be disabled by setting kern.ipc.piperesizeallowed=0.  If
  74  * that is set,  the only resize that will occur is the 0 -> SMALL_PIPE_SIZE
  75  * resize which MUST occur for reverse-direction pipes when they are
  76  * first used.
  77  *
  78  * Additional information about the current state of pipes may be obtained
  79  * from kern.ipc.pipes, kern.ipc.pipefragretry, kern.ipc.pipeallocfail,
  80  * and kern.ipc.piperesizefail.
  81  *
  82  * Locking rules:  There are two locks present here:  A mutex, used via
  83  * PIPE_LOCK, and a flag, used via pipelock().  All locking is done via
  84  * the flag, as mutexes can not persist over uiomove.  The mutex
  85  * exists only to guard access to the flag, and is not in itself a
  86  * locking mechanism.  Also note that there is only a single mutex for
  87  * both directions of a pipe.
  88  *
  89  * As pipelock() may have to sleep before it can acquire the flag, it
  90  * is important to reread all data after a call to pipelock(); everything
  91  * in the structure may have changed.
  92  */
  93
  94 #include <sys/cdefs.h>
  95 __FBSDID("$FreeBSD$");
  96
  97 #include <sys/param.h>
  98 #include <sys/systm.h>
  99 #include <sys/conf.h>
 100 #include <sys/fcntl.h>
 101 #include <sys/file.h>
 102 #include <sys/filedesc.h>
 103 #include <sys/filio.h>
 104 #include <sys/kernel.h>
 105 #include <sys/lock.h>
 106 #include <sys/mutex.h>
 107 #include <sys/ttycom.h>
 108 #include <sys/stat.h>
 109 #include <sys/malloc.h>
 110 #include <sys/poll.h>
 111 #include <sys/selinfo.h>
 112 #include <sys/signalvar.h>
 113 #include <sys/syscallsubr.h>
 114 #include <sys/sysctl.h>
 115 #include <sys/sysproto.h>
 116 #include <sys/pipe.h>
 117 #include <sys/proc.h>
 118 #include <sys/vnode.h>
 119 #include <sys/uio.h>
 120 #include <sys/user.h>
 121 #include <sys/event.h>
 122
 123 #include <security/mac/mac_framework.h>
 124
 125 #include <vm/vm.h>
 126 #include <vm/vm_param.h>
 127 #include <vm/vm_object.h>
 128 #include <vm/vm_kern.h>
 129 #include <vm/vm_extern.h>
 130 #include <vm/pmap.h>
 131 #include <vm/vm_map.h>
 132 #include <vm/vm_page.h>
 133 #include <vm/uma.h>
 134
 135 /*
 136  * Use this define if you want to disable *fancy* VM things.  Expect an
 137  * approx 30% decrease in transfer rate.  This could be useful for
 138  * NetBSD or OpenBSD.
 139  */
 140 /* #define PIPE_NODIRECT */
 141
 142 #define PIPE_PEER(pipe) \
 143         (((pipe)->pipe_state & PIPE_NAMED) ? (pipe) : ((pipe)->pipe_peer))
 144
 145 /*
 146  * interfaces to the outside world
 147  */
 148 static fo_rdwr_t        pipe_read;
 149 static fo_rdwr_t        pipe_write;
 150 static fo_truncate_t    pipe_truncate;
 151 static fo_ioctl_t       pipe_ioctl;
 152 static fo_poll_t        pipe_poll;
 153 static fo_kqfilter_t    pipe_kqfilter;
 154 static fo_stat_t        pipe_stat;
 155 static fo_close_t       pipe_close;
 156 static fo_chmod_t       pipe_chmod;
 157 static fo_chown_t       pipe_chown;
 158 static fo_fill_kinfo_t  pipe_fill_kinfo;
 159
 160 struct fileops pipeops = {
 161         .fo_read = pipe_read,
 162         .fo_write = pipe_write,
 163         .fo_truncate = pipe_truncate,
 164         .fo_ioctl = pipe_ioctl,
 165         .fo_poll = pipe_poll,
 166         .fo_kqfilter = pipe_kqfilter,
 167         .fo_stat = pipe_stat,
 168         .fo_close = pipe_close,
 169         .fo_chmod = pipe_chmod,
 170         .fo_chown = pipe_chown,
 171         .fo_sendfile = invfo_sendfile,
 172         .fo_fill_kinfo = pipe_fill_kinfo,
 173         .fo_flags = DFLAG_PASSABLE
 174 };
 175
 176 static void     filt_pipedetach(struct knote *kn);
 177 static void     filt_pipedetach_notsup(struct knote *kn);
 178 static int      filt_pipenotsup(struct knote *kn, long hint);
 179 static int      filt_piperead(struct knote *kn, long hint);
 180 static int      filt_pipewrite(struct knote *kn, long hint);
 181
 182 static struct filterops pipe_nfiltops = {
 183         .f_isfd = 1,
 184         .f_detach = filt_pipedetach_notsup,
 185         .f_event = filt_pipenotsup
 186 };
 187 static struct filterops pipe_rfiltops = {
 188         .f_isfd = 1,
 189         .f_detach = filt_pipedetach,
 190         .f_event = filt_piperead
 191 };
 192 static struct filterops pipe_wfiltops = {
 193         .f_isfd = 1,
 194         .f_detach = filt_pipedetach,
 195         .f_event = filt_pipewrite
 196 };
 197
 198 /*
 199  * Default pipe buffer size(s), this can be kind-of large now because pipe
 200  * space is pageable.  The pipe code will try to maintain locality of
 201  * reference for performance reasons, so small amounts of outstanding I/O
 202  * will not wipe the cache.
 203  */
 204 #define MINPIPESIZE (PIPE_SIZE/3)
 205 #define MAXPIPESIZE (2*PIPE_SIZE/3)
 206
 207 static long amountpipekva;
 208 static int pipefragretry;
 209 static int pipeallocfail;
 210 static int piperesizefail;
 211 static int piperesizeallowed = 1;
 212
 213 SYSCTL_LONG(_kern_ipc, OID_AUTO, maxpipekva, CTLFLAG_RDTUN | CTLFLAG_NOFETCH,
 214            &maxpipekva, 0, "Pipe KVA limit");
 215 SYSCTL_LONG(_kern_ipc, OID_AUTO, pipekva, CTLFLAG_RD,
 216            &amountpipekva, 0, "Pipe KVA usage");
 217 SYSCTL_INT(_kern_ipc, OID_AUTO, pipefragretry, CTLFLAG_RD,
 218           &pipefragretry, 0, "Pipe allocation retries due to fragmentation");
 219 SYSCTL_INT(_kern_ipc, OID_AUTO, pipeallocfail, CTLFLAG_RD,
 220           &pipeallocfail, 0, "Pipe allocation failures");
 221 SYSCTL_INT(_kern_ipc, OID_AUTO, piperesizefail, CTLFLAG_RD,
 222           &piperesizefail, 0, "Pipe resize failures");
 223 SYSCTL_INT(_kern_ipc, OID_AUTO, piperesizeallowed, CTLFLAG_RW,
 224           &piperesizeallowed, 0, "Pipe resizing allowed");
 225
 226 static void pipeinit(void *dummy __unused);
 227 static void pipeclose(struct pipe *cpipe);
 228 static void pipe_free_kmem(struct pipe *cpipe);
 229 static void pipe_create(struct pipe *pipe, int backing);
 230 static void pipe_paircreate(struct thread *td, struct pipepair **p_pp);
 231 static __inline int pipelock(struct pipe *cpipe, int catch);
 232 static __inline void pipeunlock(struct pipe *cpipe);
 233 #ifndef PIPE_NODIRECT
 234 static int pipe_build_write_buffer(struct pipe *wpipe, struct uio *uio);
 235 static void pipe_destroy_write_buffer(struct pipe *wpipe);
 236 static int pipe_direct_write(struct pipe *wpipe, struct uio *uio);
 237 static void pipe_clone_write_buffer(struct pipe *wpipe);
 238 #endif
 239 static int pipespace(struct pipe *cpipe, int size);
 240 static int pipespace_new(struct pipe *cpipe, int size);
 241
 242 static int      pipe_zone_ctor(void *mem, int size, void *arg, int flags);
 243 static int      pipe_zone_init(void *mem, int size, int flags);
 244 static void     pipe_zone_fini(void *mem, int size);
 245
 246 static uma_zone_t pipe_zone;
 247 static struct unrhdr *pipeino_unr;
 248 static dev_t pipedev_ino;
 249
 250 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_ANY, pipeinit, NULL);
 251
 252 static void
 253 pipeinit(void *dummy __unused)
 254 {
 255
 256         pipe_zone = uma_zcreate("pipe", sizeof(struct pipepair),
 257             pipe_zone_ctor, NULL, pipe_zone_init, pipe_zone_fini,
 258             UMA_ALIGN_PTR, 0);
 259         KASSERT(pipe_zone != NULL, ("pipe_zone not initialized"));
 260         pipeino_unr = new_unrhdr(1, INT32_MAX, NULL);
 261         KASSERT(pipeino_unr != NULL, ("pipe fake inodes not initialized"));
 262         pipedev_ino = devfs_alloc_cdp_inode();
 263         KASSERT(pipedev_ino > 0, ("pipe dev inode not initialized"));
 264 }
 265
 266 static int
 267 pipe_zone_ctor(void *mem, int size, void *arg, int flags)
 268 {
 269         struct pipepair *pp;
 270         struct pipe *rpipe, *wpipe;
 271
 272         KASSERT(size == sizeof(*pp), ("pipe_zone_ctor: wrong size"));
 273
 274         pp = (struct pipepair *)mem;
 275
 276         /*
 277          * We zero both pipe endpoints to make sure all the kmem pointers
 278          * are NULL, flag fields are zero'd, etc.  We timestamp both
 279          * endpoints with the same time.
 280          */
 281         rpipe = &pp->pp_rpipe;
 282         bzero(rpipe, sizeof(*rpipe));
 283         vfs_timestamp(&rpipe->pipe_ctime);
 284         rpipe->pipe_atime = rpipe->pipe_mtime = rpipe->pipe_ctime;
 285
 286         wpipe = &pp->pp_wpipe;
 287         bzero(wpipe, sizeof(*wpipe));
 288         wpipe->pipe_ctime = rpipe->pipe_ctime;
 289         wpipe->pipe_atime = wpipe->pipe_mtime = rpipe->pipe_ctime;
 290
 291         rpipe->pipe_peer = wpipe;
 292         rpipe->pipe_pair = pp;
 293         wpipe->pipe_peer = rpipe;
 294         wpipe->pipe_pair = pp;
 295
 296         /*
 297          * Mark both endpoints as present; they will later get free'd
 298          * one at a time.  When both are free'd, then the whole pair
 299          * is released.
 300          */
 301         rpipe->pipe_present = PIPE_ACTIVE;
 302         wpipe->pipe_present = PIPE_ACTIVE;
 303
 304         /*
 305          * Eventually, the MAC Framework may initialize the label
 306          * in ctor or init, but for now we do it elswhere to avoid
 307          * blocking in ctor or init.
 308          */
 309         pp->pp_label = NULL;
 310
 311         return (0);
 312 }
 313
 314 static int
 315 pipe_zone_init(void *mem, int size, int flags)
 316 {
 317         struct pipepair *pp;
 318
 319         KASSERT(size == sizeof(*pp), ("pipe_zone_init: wrong size"));
 320
 321         pp = (struct pipepair *)mem;
 322
 323         mtx_init(&pp->pp_mtx, "pipe mutex", NULL, MTX_DEF | MTX_NEW);
 324         return (0);
 325 }
 326
 327 static void
 328 pipe_zone_fini(void *mem, int size)
 329 {
 330         struct pipepair *pp;
 331
 332         KASSERT(size == sizeof(*pp), ("pipe_zone_fini: wrong size"));
 333
 334         pp = (struct pipepair *)mem;
 335
 336         mtx_destroy(&pp->pp_mtx);
 337 }
 338
 339 static void
 340 pipe_paircreate(struct thread *td, struct pipepair **p_pp)
 341 {
 342         struct pipepair *pp;
 343         struct pipe *rpipe, *wpipe;
 344
 345         *p_pp = pp = uma_zalloc(pipe_zone, M_WAITOK);
 346 #ifdef MAC
 347         /*
 348          * The MAC label is shared between the connected endpoints.  As a
 349          * result mac_pipe_init() and mac_pipe_create() are called once
 350          * for the pair, and not on the endpoints.
 351          */
 352         mac_pipe_init(pp);
 353         mac_pipe_create(td->td_ucred, pp);
 354 #endif
 355         rpipe = &pp->pp_rpipe;
 356         wpipe = &pp->pp_wpipe;
 357
 358         knlist_init_mtx(&rpipe->pipe_sel.si_note, PIPE_MTX(rpipe));
 359         knlist_init_mtx(&wpipe->pipe_sel.si_note, PIPE_MTX(wpipe));
 360
 361         /* Only the forward direction pipe is backed by default */
 362         pipe_create(rpipe, 1);
 363         pipe_create(wpipe, 0);
 364
 365         rpipe->pipe_state |= PIPE_DIRECTOK;
 366         wpipe->pipe_state |= PIPE_DIRECTOK;
 367 }
 368
 369 void
 370 pipe_named_ctor(struct pipe **ppipe, struct thread *td)
 371 {
 372         struct pipepair *pp;
 373
 374         pipe_paircreate(td, &pp);
 375         pp->pp_rpipe.pipe_state |= PIPE_NAMED;
 376         *ppipe = &pp->pp_rpipe;
 377 }
 378
 379 void
 380 pipe_dtor(struct pipe *dpipe)
 381 {
 382         struct pipe *peer;
 383         ino_t ino;
 384
 385         ino = dpipe->pipe_ino;
 386         peer = (dpipe->pipe_state & PIPE_NAMED) != 0 ? dpipe->pipe_peer : NULL;
 387         funsetown(&dpipe->pipe_sigio);
 388         pipeclose(dpipe);
 389         if (peer != NULL) {
 390                 funsetown(&peer->pipe_sigio);
 391                 pipeclose(peer);
 392         }
 393         if (ino != 0 && ino != (ino_t)-1)
 394                 free_unr(pipeino_unr, ino);
 395 }
 396
 397 /*
 398  * The pipe system call for the DTYPE_PIPE type of pipes.  If we fail, let
 399  * the zone pick up the pieces via pipeclose().
 400  */
 401 int
 402 kern_pipe(struct thread *td, int fildes[2], int flags, struct filecaps *fcaps1,
 403     struct filecaps *fcaps2)
 404 {
 405         struct file *rf, *wf;
 406         struct pipe *rpipe, *wpipe;
 407         struct pipepair *pp;
 408         int fd, fflags, error;
 409
 410         pipe_paircreate(td, &pp);
 411         rpipe = &pp->pp_rpipe;
 412         wpipe = &pp->pp_wpipe;
 413         error = falloc_caps(td, &rf, &fd, flags, fcaps1);
 414         if (error) {
 415                 pipeclose(rpipe);
 416                 pipeclose(wpipe);
 417                 return (error);
 418         }
 419         /* An extra reference on `rf' has been held for us by falloc_caps(). */
 420         fildes[0] = fd;
 421
 422         fflags = FREAD | FWRITE;
 423         if ((flags & O_NONBLOCK) != 0)
 424                 fflags |= FNONBLOCK;
 425
 426         /*
 427          * Warning: once we've gotten past allocation of the fd for the
 428          * read-side, we can only drop the read side via fdrop() in order
 429          * to avoid races against processes which manage to dup() the read
 430          * side while we are blocked trying to allocate the write side.
 431          */
 432         finit(rf, fflags, DTYPE_PIPE, rpipe, &pipeops);
 433         error = falloc_caps(td, &wf, &fd, flags, fcaps2);
 434         if (error) {
 435                 fdclose(td, rf, fildes[0]);
 436                 fdrop(rf, td);
 437                 /* rpipe has been closed by fdrop(). */
 438                 pipeclose(wpipe);
 439                 return (error);
 440         }
 441         /* An extra reference on `wf' has been held for us by falloc_caps(). */
 442         finit(wf, fflags, DTYPE_PIPE, wpipe, &pipeops);
 443         fdrop(wf, td);
 444         fildes[1] = fd;
 445         fdrop(rf, td);
 446
 447         return (0);
 448 }
 449
 450 #ifdef COMPAT_FREEBSD10
 451 /* ARGSUSED */
 452 int
 453 freebsd10_pipe(struct thread *td, struct freebsd10_pipe_args *uap __unused)
 454 {
 455         int error;
 456         int fildes[2];
 457
 458         error = kern_pipe(td, fildes, 0, NULL, NULL);
 459         if (error)
 460                 return (error);
 461
 462         td->td_retval[0] = fildes[0];
 463         td->td_retval[1] = fildes[1];
 464
 465         return (0);
 466 }
 467 #endif
 468
 469 int
 470 sys_pipe2(struct thread *td, struct pipe2_args *uap)
 471 {
 472         int error, fildes[2];
 473
 474         if (uap->flags & ~(O_CLOEXEC | O_NONBLOCK))
 475                 return (EINVAL);
 476         error = kern_pipe(td, fildes, uap->flags, NULL, NULL);
 477         if (error)
 478                 return (error);
 479         error = copyout(fildes, uap->fildes, 2 * sizeof(int));
 480         if (error) {
 481                 (void)kern_close(td, fildes[0]);
 482                 (void)kern_close(td, fildes[1]);
 483         }
 484         return (error);
 485 }
 486
 487 /*
 488  * Allocate kva for pipe circular buffer, the space is pageable
 489  * This routine will 'realloc' the size of a pipe safely, if it fails
 490  * it will retain the old buffer.
 491  * If it fails it will return ENOMEM.
 492  */
 493 static int
 494 pipespace_new(cpipe, size)
 495         struct pipe *cpipe;
 496         int size;
 497 {
 498         caddr_t buffer;
 499         int error, cnt, firstseg;
 500         static int curfail = 0;
 501         static struct timeval lastfail;
 502
 503         KASSERT(!mtx_owned(PIPE_MTX(cpipe)), ("pipespace: pipe mutex locked"));
 504         KASSERT(!(cpipe->pipe_state & PIPE_DIRECTW),
 505                 ("pipespace: resize of direct writes not allowed"));
 506 retry:
 507         cnt = cpipe->pipe_buffer.cnt;
 508         if (cnt > size)
 509                 size = cnt;
 510
 511         size = round_page(size);
 512         buffer = (caddr_t) vm_map_min(pipe_map);
 513
 514         error = vm_map_find(pipe_map, NULL, 0,
 515                 (vm_offset_t *) &buffer, size, 0, VMFS_ANY_SPACE,
 516                 VM_PROT_ALL, VM_PROT_ALL, 0);
 517         if (error != KERN_SUCCESS) {
 518                 if ((cpipe->pipe_buffer.buffer == NULL) &&
 519                         (size > SMALL_PIPE_SIZE)) {
 520                         size = SMALL_PIPE_SIZE;
 521                         pipefragretry++;
 522                         goto retry;
 523                 }
 524                 if (cpipe->pipe_buffer.buffer == NULL) {
 525                         pipeallocfail++;
 526                         if (ppsratecheck(&lastfail, &curfail, 1))
 527                                 printf("kern.ipc.maxpipekva exceeded; see tuning(7)\n");
 528                 } else {
 529                         piperesizefail++;
 530                 }
 531                 return (ENOMEM);
 532         }
 533
 534         /* copy data, then free old resources if we're resizing */
 535         if (cnt > 0) {
 536                 if (cpipe->pipe_buffer.in <= cpipe->pipe_buffer.out) {
 537                         firstseg = cpipe->pipe_buffer.size - cpipe->pipe_buffer.out;
 538                         bcopy(&cpipe->pipe_buffer.buffer[cpipe->pipe_buffer.out],
 539                                 buffer, firstseg);
 540                         if ((cnt - firstseg) > 0)
 541                                 bcopy(cpipe->pipe_buffer.buffer, &buffer[firstseg],
 542                                         cpipe->pipe_buffer.in);
 543                 } else {
 544                         bcopy(&cpipe->pipe_buffer.buffer[cpipe->pipe_buffer.out],
 545                                 buffer, cnt);
 546                 }
 547         }
 548         pipe_free_kmem(cpipe);
 549         cpipe->pipe_buffer.buffer = buffer;
 550         cpipe->pipe_buffer.size = size;
 551         cpipe->pipe_buffer.in = cnt;
 552         cpipe->pipe_buffer.out = 0;
 553         cpipe->pipe_buffer.cnt = cnt;
 554         atomic_add_long(&amountpipekva, cpipe->pipe_buffer.size);
 555         return (0);
 556 }
 557
 558 /*
 559  * Wrapper for pipespace_new() that performs locking assertions.
 560  */
 561 static int
 562 pipespace(cpipe, size)
 563         struct pipe *cpipe;
 564         int size;
 565 {
 566
 567         KASSERT(cpipe->pipe_state & PIPE_LOCKFL,
 568                 ("Unlocked pipe passed to pipespace"));
 569         return (pipespace_new(cpipe, size));
 570 }
 571
 572 /*
 573  * lock a pipe for I/O, blocking other access
 574  */
 575 static __inline int
 576 pipelock(cpipe, catch)
 577         struct pipe *cpipe;
 578         int catch;
 579 {
 580         int error;
 581
 582         PIPE_LOCK_ASSERT(cpipe, MA_OWNED);
 583         while (cpipe->pipe_state & PIPE_LOCKFL) {
 584                 cpipe->pipe_state |= PIPE_LWANT;
 585                 error = msleep(cpipe, PIPE_MTX(cpipe),
 586                     catch ? (PRIBIO | PCATCH) : PRIBIO,
 587                     "pipelk", 0);
 588                 if (error != 0)
 589                         return (error);
 590         }
 591         cpipe->pipe_state |= PIPE_LOCKFL;
 592         return (0);
 593 }
 594
 595 /*
 596  * unlock a pipe I/O lock
 597  */
 598 static __inline void
 599 pipeunlock(cpipe)
 600         struct pipe *cpipe;
 601 {
 602
 603         PIPE_LOCK_ASSERT(cpipe, MA_OWNED);
 604         KASSERT(cpipe->pipe_state & PIPE_LOCKFL,
 605                 ("Unlocked pipe passed to pipeunlock"));
 606         cpipe->pipe_state &= ~PIPE_LOCKFL;
 607         if (cpipe->pipe_state & PIPE_LWANT) {
 608                 cpipe->pipe_state &= ~PIPE_LWANT;
 609                 wakeup(cpipe);
 610         }
 611 }
 612
 613 void
 614 pipeselwakeup(cpipe)
 615         struct pipe *cpipe;
 616 {
 617
 618         PIPE_LOCK_ASSERT(cpipe, MA_OWNED);
 619         if (cpipe->pipe_state & PIPE_SEL) {
 620                 selwakeuppri(&cpipe->pipe_sel, PSOCK);
 621                 if (!SEL_WAITING(&cpipe->pipe_sel))
 622                         cpipe->pipe_state &= ~PIPE_SEL;
 623         }
 624         if ((cpipe->pipe_state & PIPE_ASYNC) && cpipe->pipe_sigio)
 625                 pgsigio(&cpipe->pipe_sigio, SIGIO, 0);
 626         KNOTE_LOCKED(&cpipe->pipe_sel.si_note, 0);
 627 }
 628
 629 /*
 630  * Initialize and allocate VM and memory for pipe.  The structure
 631  * will start out zero'd from the ctor, so we just manage the kmem.
 632  */
 633 static void
 634 pipe_create(pipe, backing)
 635         struct pipe *pipe;
 636         int backing;
 637 {
 638
 639         if (backing) {
 640                 /*
 641                  * Note that these functions can fail if pipe map is exhausted
 642                  * (as a result of too many pipes created), but we ignore the
 643                  * error as it is not fatal and could be provoked by
 644                  * unprivileged users. The only consequence is worse performance
 645                  * with given pipe.
 646                  */
 647                 if (amountpipekva > maxpipekva / 2)
 648                         (void)pipespace_new(pipe, SMALL_PIPE_SIZE);
 649                 else
 650                         (void)pipespace_new(pipe, PIPE_SIZE);
 651         }
 652
 653         pipe->pipe_ino = -1;
 654 }
 655
 656 /* ARGSUSED */
 657 static int
 658 pipe_read(fp, uio, active_cred, flags, td)
 659         struct file *fp;
 660         struct uio *uio;
 661         struct ucred *active_cred;
 662         struct thread *td;
 663         int flags;
 664 {
 665         struct pipe *rpipe;
 666         int error;
 667         int nread = 0;
 668         int size;
 669
 670         rpipe = fp->f_data;
 671         PIPE_LOCK(rpipe);
 672         ++rpipe->pipe_busy;
 673         error = pipelock(rpipe, 1);
 674         if (error)
 675                 goto unlocked_error;
 676
 677 #ifdef MAC
 678         error = mac_pipe_check_read(active_cred, rpipe->pipe_pair);
 679         if (error)
 680                 goto locked_error;
 681 #endif
 682         if (amountpipekva > (3 * maxpipekva) / 4) {
 683                 if (!(rpipe->pipe_state & PIPE_DIRECTW) &&
 684                         (rpipe->pipe_buffer.size > SMALL_PIPE_SIZE) &&
 685                         (rpipe->pipe_buffer.cnt <= SMALL_PIPE_SIZE) &&
 686                         (piperesizeallowed == 1)) {
 687                         PIPE_UNLOCK(rpipe);
 688                         pipespace(rpipe, SMALL_PIPE_SIZE);
 689                         PIPE_LOCK(rpipe);
 690                 }
 691         }
 692
 693         while (uio->uio_resid) {
 694                 /*
 695                  * normal pipe buffer receive
 696                  */
 697                 if (rpipe->pipe_buffer.cnt > 0) {
 698                         size = rpipe->pipe_buffer.size - rpipe->pipe_buffer.out;
 699                         if (size > rpipe->pipe_buffer.cnt)
 700                                 size = rpipe->pipe_buffer.cnt;
 701                         if (size > uio->uio_resid)
 702                                 size = uio->uio_resid;
 703
 704                         PIPE_UNLOCK(rpipe);
 705                         error = uiomove(
 706                             &rpipe->pipe_buffer.buffer[rpipe->pipe_buffer.out],
 707                             size, uio);
 708                         PIPE_LOCK(rpipe);
 709                         if (error)
 710                                 break;
 711
 712                         rpipe->pipe_buffer.out += size;
 713                         if (rpipe->pipe_buffer.out >= rpipe->pipe_buffer.size)
 714                                 rpipe->pipe_buffer.out = 0;
 715
 716                         rpipe->pipe_buffer.cnt -= size;
 717
 718                         /*
 719                          * If there is no more to read in the pipe, reset
 720                          * its pointers to the beginning.  This improves
 721                          * cache hit stats.
 722                          */
 723                         if (rpipe->pipe_buffer.cnt == 0) {
 724                                 rpipe->pipe_buffer.in = 0;
 725                                 rpipe->pipe_buffer.out = 0;
 726                         }
 727                         nread += size;
 728 #ifndef PIPE_NODIRECT
 729                 /*
 730                  * Direct copy, bypassing a kernel buffer.
 731                  */
 732                 } else if ((size = rpipe->pipe_map.cnt) &&
 733                            (rpipe->pipe_state & PIPE_DIRECTW)) {
 734                         if (size > uio->uio_resid)
 735                                 size = (u_int) uio->uio_resid;
 736
 737                         PIPE_UNLOCK(rpipe);
 738                         error = uiomove_fromphys(rpipe->pipe_map.ms,
 739                             rpipe->pipe_map.pos, size, uio);
 740                         PIPE_LOCK(rpipe);
 741                         if (error)
 742                                 break;
 743                         nread += size;
 744                         rpipe->pipe_map.pos += size;
 745                         rpipe->pipe_map.cnt -= size;
 746                         if (rpipe->pipe_map.cnt == 0) {
 747                                 rpipe->pipe_state &= ~(PIPE_DIRECTW|PIPE_WANTW);
 748                                 wakeup(rpipe);
 749                         }
 750 #endif
 751                 } else {
 752                         /*
 753                          * detect EOF condition
 754                          * read returns 0 on EOF, no need to set error
 755                          */
 756                         if (rpipe->pipe_state & PIPE_EOF)
 757                                 break;
 758
 759                         /*
 760                          * If the "write-side" has been blocked, wake it up now.
 761                          */
 762                         if (rpipe->pipe_state & PIPE_WANTW) {
 763                                 rpipe->pipe_state &= ~PIPE_WANTW;
 764                                 wakeup(rpipe);
 765                         }
 766
 767                         /*
 768                          * Break if some data was read.
 769                          */
 770                         if (nread > 0)
 771                                 break;
 772
 773                         /*
 774                          * Unlock the pipe buffer for our remaining processing.
 775                          * We will either break out with an error or we will
 776                          * sleep and relock to loop.
 777                          */
 778                         pipeunlock(rpipe);
 779
 780                         /*
 781                          * Handle non-blocking mode operation or
 782                          * wait for more data.
 783                          */
 784                         if (fp->f_flag & FNONBLOCK) {
 785                                 error = EAGAIN;
 786                         } else {
 787                                 rpipe->pipe_state |= PIPE_WANTR;
 788                                 if ((error = msleep(rpipe, PIPE_MTX(rpipe),
 789                                     PRIBIO | PCATCH,
 790                                     "piperd", 0)) == 0)
 791                                         error = pipelock(rpipe, 1);
 792                         }
 793                         if (error)
 794                                 goto unlocked_error;
 795                 }
 796         }
 797 #ifdef MAC
 798 locked_error:
 799 #endif
 800         pipeunlock(rpipe);
 801
 802         /* XXX: should probably do this before getting any locks. */
 803         if (error == 0)
 804                 vfs_timestamp(&rpipe->pipe_atime);
 805 unlocked_error:
 806         --rpipe->pipe_busy;
 807
 808         /*
 809          * PIPE_WANT processing only makes sense if pipe_busy is 0.
 810          */
 811         if ((rpipe->pipe_busy == 0) && (rpipe->pipe_state & PIPE_WANT)) {
 812                 rpipe->pipe_state &= ~(PIPE_WANT|PIPE_WANTW);
 813                 wakeup(rpipe);
 814         } else if (rpipe->pipe_buffer.cnt < MINPIPESIZE) {
 815                 /*
 816                  * Handle write blocking hysteresis.
 817                  */
 818                 if (rpipe->pipe_state & PIPE_WANTW) {
 819                         rpipe->pipe_state &= ~PIPE_WANTW;
 820                         wakeup(rpipe);
 821                 }
 822         }
 823
 824         if ((rpipe->pipe_buffer.size - rpipe->pipe_buffer.cnt) >= PIPE_BUF)
 825                 pipeselwakeup(rpipe);
 826
 827         PIPE_UNLOCK(rpipe);
 828         return (error);
 829 }
 830
 831 #ifndef PIPE_NODIRECT
 832 /*
 833  * Map the sending processes' buffer into kernel space and wire it.
 834  * This is similar to a physical write operation.
 835  */
 836 static int
 837 pipe_build_write_buffer(wpipe, uio)
 838         struct pipe *wpipe;
 839         struct uio *uio;
 840 {
 841         u_int size;
 842         int i;
 843
 844         PIPE_LOCK_ASSERT(wpipe, MA_NOTOWNED);
 845         KASSERT(wpipe->pipe_state & PIPE_DIRECTW,
 846                 ("Clone attempt on non-direct write pipe!"));
 847
 848         if (uio->uio_iov->iov_len > wpipe->pipe_buffer.size)
 849                 size = wpipe->pipe_buffer.size;
 850         else
 851                 size = uio->uio_iov->iov_len;
 852
 853         if ((i = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map,
 854             (vm_offset_t)uio->uio_iov->iov_base, size, VM_PROT_READ,
 855             wpipe->pipe_map.ms, PIPENPAGES)) < 0)
 856                 return (EFAULT);
 857
 858 /*
 859  * set up the control block
 860  */
 861         wpipe->pipe_map.npages = i;
 862         wpipe->pipe_map.pos =
 863             ((vm_offset_t) uio->uio_iov->iov_base) & PAGE_MASK;
 864         wpipe->pipe_map.cnt = size;
 865
 866 /*
 867  * and update the uio data
 868  */
 869
 870         uio->uio_iov->iov_len -= size;
 871         uio->uio_iov->iov_base = (char *)uio->uio_iov->iov_base + size;
 872         if (uio->uio_iov->iov_len == 0)
 873                 uio->uio_iov++;
 874         uio->uio_resid -= size;
 875         uio->uio_offset += size;
 876         return (0);
 877 }
 878
 879 /*
 880  * unmap and unwire the process buffer
 881  */
 882 static void
 883 pipe_destroy_write_buffer(wpipe)
 884         struct pipe *wpipe;
 885 {
 886
 887         PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
 888         vm_page_unhold_pages(wpipe->pipe_map.ms, wpipe->pipe_map.npages);
 889         wpipe->pipe_map.npages = 0;
 890 }
 891
 892 /*
 893  * In the case of a signal, the writing process might go away.  This
 894  * code copies the data into the circular buffer so that the source
 895  * pages can be freed without loss of data.
 896  */
 897 static void
 898 pipe_clone_write_buffer(wpipe)
 899         struct pipe *wpipe;
 900 {
 901         struct uio uio;
 902         struct iovec iov;
 903         int size;
 904         int pos;
 905
 906         PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
 907         size = wpipe->pipe_map.cnt;
 908         pos = wpipe->pipe_map.pos;
 909
 910         wpipe->pipe_buffer.in = size;
 911         wpipe->pipe_buffer.out = 0;
 912         wpipe->pipe_buffer.cnt = size;
 913         wpipe->pipe_state &= ~PIPE_DIRECTW;
 914
 915         PIPE_UNLOCK(wpipe);
 916         iov.iov_base = wpipe->pipe_buffer.buffer;
 917         iov.iov_len = size;
 918         uio.uio_iov = &iov;
 919         uio.uio_iovcnt = 1;
 920         uio.uio_offset = 0;
 921         uio.uio_resid = size;
 922         uio.uio_segflg = UIO_SYSSPACE;
 923         uio.uio_rw = UIO_READ;
 924         uio.uio_td = curthread;
 925         uiomove_fromphys(wpipe->pipe_map.ms, pos, size, &uio);
 926         PIPE_LOCK(wpipe);
 927         pipe_destroy_write_buffer(wpipe);
 928 }
 929
 930 /*
 931  * This implements the pipe buffer write mechanism.  Note that only
 932  * a direct write OR a normal pipe write can be pending at any given time.
 933  * If there are any characters in the pipe buffer, the direct write will
 934  * be deferred until the receiving process grabs all of the bytes from
 935  * the pipe buffer.  Then the direct mapping write is set-up.
 936  */
 937 static int
 938 pipe_direct_write(wpipe, uio)
 939         struct pipe *wpipe;
 940         struct uio *uio;
 941 {
 942         int error;
 943
 944 retry:
 945         PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
 946         error = pipelock(wpipe, 1);
 947         if (error != 0)
 948                 goto error1;
 949         if ((wpipe->pipe_state & PIPE_EOF) != 0) {
 950                 error = EPIPE;
 951                 pipeunlock(wpipe);
 952                 goto error1;
 953         }
 954         while (wpipe->pipe_state & PIPE_DIRECTW) {
 955                 if (wpipe->pipe_state & PIPE_WANTR) {
 956                         wpipe->pipe_state &= ~PIPE_WANTR;
 957                         wakeup(wpipe);
 958                 }
 959                 pipeselwakeup(wpipe);
 960                 wpipe->pipe_state |= PIPE_WANTW;
 961                 pipeunlock(wpipe);
 962                 error = msleep(wpipe, PIPE_MTX(wpipe),
 963                     PRIBIO | PCATCH, "pipdww", 0);
 964                 if (error)
 965                         goto error1;
 966                 else
 967                         goto retry;
 968         }
 969         wpipe->pipe_map.cnt = 0;        /* transfer not ready yet */
 970         if (wpipe->pipe_buffer.cnt > 0) {
 971                 if (wpipe->pipe_state & PIPE_WANTR) {
 972                         wpipe->pipe_state &= ~PIPE_WANTR;
 973                         wakeup(wpipe);
 974                 }
 975                 pipeselwakeup(wpipe);
 976                 wpipe->pipe_state |= PIPE_WANTW;
 977                 pipeunlock(wpipe);
 978                 error = msleep(wpipe, PIPE_MTX(wpipe),
 979                     PRIBIO | PCATCH, "pipdwc", 0);
 980                 if (error)
 981                         goto error1;
 982                 else
 983                         goto retry;
 984         }
 985
 986         wpipe->pipe_state |= PIPE_DIRECTW;
 987
 988         PIPE_UNLOCK(wpipe);
 989         error = pipe_build_write_buffer(wpipe, uio);
 990         PIPE_LOCK(wpipe);
 991         if (error) {
 992                 wpipe->pipe_state &= ~PIPE_DIRECTW;
 993                 pipeunlock(wpipe);
 994                 goto error1;
 995         }
 996
 997         error = 0;
 998         while (!error && (wpipe->pipe_state & PIPE_DIRECTW)) {
 999                 if (wpipe->pipe_state & PIPE_EOF) {
1000                         pipe_destroy_write_buffer(wpipe);
1001                         pipeselwakeup(wpipe);
1002                         pipeunlock(wpipe);
1003                         error = EPIPE;
1004                         goto error1;
1005                 }
1006                 if (wpipe->pipe_state & PIPE_WANTR) {
1007                         wpipe->pipe_state &= ~PIPE_WANTR;
1008                         wakeup(wpipe);
1009                 }
1010                 pipeselwakeup(wpipe);
1011                 wpipe->pipe_state |= PIPE_WANTW;
1012                 pipeunlock(wpipe);
1013                 error = msleep(wpipe, PIPE_MTX(wpipe), PRIBIO | PCATCH,
1014                     "pipdwt", 0);
1015                 pipelock(wpipe, 0);
1016         }
1017
1018         if (wpipe->pipe_state & PIPE_EOF)
1019                 error = EPIPE;
1020         if (wpipe->pipe_state & PIPE_DIRECTW) {
1021                 /*
1022                  * this bit of trickery substitutes a kernel buffer for
1023                  * the process that might be going away.
1024                  */
1025                 pipe_clone_write_buffer(wpipe);
1026         } else {
1027                 pipe_destroy_write_buffer(wpipe);
1028         }
1029         pipeunlock(wpipe);
1030         return (error);
1031
1032 error1:
1033         wakeup(wpipe);
1034         return (error);
1035 }
1036 #endif
1037
1038 static int
1039 pipe_write(fp, uio, active_cred, flags, td)
1040         struct file *fp;
1041         struct uio *uio;
1042         struct ucred *active_cred;
1043         struct thread *td;
1044         int flags;
1045 {
1046         int error = 0;
1047         int desiredsize;
1048         ssize_t orig_resid;
1049         struct pipe *wpipe, *rpipe;
1050
1051         rpipe = fp->f_data;
1052         wpipe = PIPE_PEER(rpipe);
1053         PIPE_LOCK(rpipe);
1054         error = pipelock(wpipe, 1);
1055         if (error) {
1056                 PIPE_UNLOCK(rpipe);
1057                 return (error);
1058         }
1059         /*
1060          * detect loss of pipe read side, issue SIGPIPE if lost.
1061          */
1062         if (wpipe->pipe_present != PIPE_ACTIVE ||
1063             (wpipe->pipe_state & PIPE_EOF)) {
1064                 pipeunlock(wpipe);
1065                 PIPE_UNLOCK(rpipe);
1066                 return (EPIPE);
1067         }
1068 #ifdef MAC
1069         error = mac_pipe_check_write(active_cred, wpipe->pipe_pair);
1070         if (error) {
1071                 pipeunlock(wpipe);
1072                 PIPE_UNLOCK(rpipe);
1073                 return (error);
1074         }
1075 #endif
1076         ++wpipe->pipe_busy;
1077
1078         /* Choose a larger size if it's advantageous */
1079         desiredsize = max(SMALL_PIPE_SIZE, wpipe->pipe_buffer.size);
1080         while (desiredsize < wpipe->pipe_buffer.cnt + uio->uio_resid) {
1081                 if (piperesizeallowed != 1)
1082                         break;
1083                 if (amountpipekva > maxpipekva / 2)
1084                         break;
1085                 if (desiredsize == BIG_PIPE_SIZE)
1086                         break;
1087                 desiredsize = desiredsize * 2;
1088         }
1089
1090         /* Choose a smaller size if we're in a OOM situation */
1091         if ((amountpipekva > (3 * maxpipekva) / 4) &&
1092                 (wpipe->pipe_buffer.size > SMALL_PIPE_SIZE) &&
1093                 (wpipe->pipe_buffer.cnt <= SMALL_PIPE_SIZE) &&
1094                 (piperesizeallowed == 1))
1095                 desiredsize = SMALL_PIPE_SIZE;
1096
1097         /* Resize if the above determined that a new size was necessary */
1098         if ((desiredsize != wpipe->pipe_buffer.size) &&
1099                 ((wpipe->pipe_state & PIPE_DIRECTW) == 0)) {
1100                 PIPE_UNLOCK(wpipe);
1101                 pipespace(wpipe, desiredsize);
1102                 PIPE_LOCK(wpipe);
1103         }
1104         if (wpipe->pipe_buffer.size == 0) {
1105                 /*
1106                  * This can only happen for reverse direction use of pipes
1107                  * in a complete OOM situation.
1108                  */
1109                 error = ENOMEM;
1110                 --wpipe->pipe_busy;
1111                 pipeunlock(wpipe);
1112                 PIPE_UNLOCK(wpipe);
1113                 return (error);
1114         }
1115
1116         pipeunlock(wpipe);
1117
1118         orig_resid = uio->uio_resid;
1119
1120         while (uio->uio_resid) {
1121                 int space;
1122
1123                 pipelock(wpipe, 0);
1124                 if (wpipe->pipe_state & PIPE_EOF) {
1125                         pipeunlock(wpipe);
1126                         error = EPIPE;
1127                         break;
1128                 }
1129 #ifndef PIPE_NODIRECT
1130                 /*
1131                  * If the transfer is large, we can gain performance if
1132                  * we do process-to-process copies directly.
1133                  * If the write is non-blocking, we don't use the
1134                  * direct write mechanism.
1135                  *
1136                  * The direct write mechanism will detect the reader going
1137                  * away on us.
1138                  */
1139                 if (uio->uio_segflg == UIO_USERSPACE &&
1140                     uio->uio_iov->iov_len >= PIPE_MINDIRECT &&
1141                     wpipe->pipe_buffer.size >= PIPE_MINDIRECT &&
1142                     (fp->f_flag & FNONBLOCK) == 0) {
1143                         pipeunlock(wpipe);
1144                         error = pipe_direct_write(wpipe, uio);
1145                         if (error)
1146                                 break;
1147                         continue;
1148                 }
1149 #endif
1150
1151                 /*
1152                  * Pipe buffered writes cannot be coincidental with
1153                  * direct writes.  We wait until the currently executing
1154                  * direct write is completed before we start filling the
1155                  * pipe buffer.  We break out if a signal occurs or the
1156                  * reader goes away.
1157                  */
1158                 if (wpipe->pipe_state & PIPE_DIRECTW) {
1159                         if (wpipe->pipe_state & PIPE_WANTR) {
1160                                 wpipe->pipe_state &= ~PIPE_WANTR;
1161                                 wakeup(wpipe);
1162                         }
1163                         pipeselwakeup(wpipe);
1164                         wpipe->pipe_state |= PIPE_WANTW;
1165                         pipeunlock(wpipe);
1166                         error = msleep(wpipe, PIPE_MTX(rpipe), PRIBIO | PCATCH,
1167                             "pipbww", 0);
1168                         if (error)
1169                                 break;
1170                         else
1171                                 continue;
1172                 }
1173
1174                 space = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt;
1175
1176                 /* Writes of size <= PIPE_BUF must be atomic. */
1177                 if ((space < uio->uio_resid) && (orig_resid <= PIPE_BUF))
1178                         space = 0;
1179
1180                 if (space > 0) {
1181                         int size;       /* Transfer size */
1182                         int segsize;    /* first segment to transfer */
1183
1184                         /*
1185                          * Transfer size is minimum of uio transfer
1186                          * and free space in pipe buffer.
1187                          */
1188                         if (space > uio->uio_resid)
1189                                 size = uio->uio_resid;
1190                         else
1191                                 size = space;
1192                         /*
1193                          * First segment to transfer is minimum of
1194                          * transfer size and contiguous space in
1195                          * pipe buffer.  If first segment to transfer
1196                          * is less than the transfer size, we've got
1197                          * a wraparound in the buffer.
1198                          */
1199                         segsize = wpipe->pipe_buffer.size -
1200                                 wpipe->pipe_buffer.in;
1201                         if (segsize > size)
1202                                 segsize = size;
1203
1204                         /* Transfer first segment */
1205
1206                         PIPE_UNLOCK(rpipe);
1207                         error = uiomove(&wpipe->pipe_buffer.buffer[wpipe->pipe_buffer.in],
1208                                         segsize, uio);
1209                         PIPE_LOCK(rpipe);
1210
1211                         if (error == 0 && segsize < size) {
1212                                 KASSERT(wpipe->pipe_buffer.in + segsize ==
1213                                         wpipe->pipe_buffer.size,
1214                                         ("Pipe buffer wraparound disappeared"));
1215                                 /*
1216                                  * Transfer remaining part now, to
1217                                  * support atomic writes.  Wraparound
1218                                  * happened.
1219                                  */
1220
1221                                 PIPE_UNLOCK(rpipe);
1222                                 error = uiomove(
1223                                     &wpipe->pipe_buffer.buffer[0],
1224                                     size - segsize, uio);
1225                                 PIPE_LOCK(rpipe);
1226                         }
1227                         if (error == 0) {
1228                                 wpipe->pipe_buffer.in += size;
1229                                 if (wpipe->pipe_buffer.in >=
1230                                     wpipe->pipe_buffer.size) {
1231                                         KASSERT(wpipe->pipe_buffer.in ==
1232                                                 size - segsize +
1233                                                 wpipe->pipe_buffer.size,
1234                                                 ("Expected wraparound bad"));
1235                                         wpipe->pipe_buffer.in = size - segsize;
1236                                 }
1237
1238                                 wpipe->pipe_buffer.cnt += size;
1239                                 KASSERT(wpipe->pipe_buffer.cnt <=
1240                                         wpipe->pipe_buffer.size,
1241                                         ("Pipe buffer overflow"));
1242                         }
1243                         pipeunlock(wpipe);
1244                         if (error != 0)
1245                                 break;
1246                 } else {
1247                         /*
1248                          * If the "read-side" has been blocked, wake it up now.
1249                          */
1250                         if (wpipe->pipe_state & PIPE_WANTR) {
1251                                 wpipe->pipe_state &= ~PIPE_WANTR;
1252                                 wakeup(wpipe);
1253                         }
1254
1255                         /*
1256                          * don't block on non-blocking I/O
1257                          */
1258                         if (fp->f_flag & FNONBLOCK) {
1259                                 error = EAGAIN;
1260                                 pipeunlock(wpipe);
1261                                 break;
1262                         }
1263
1264                         /*
1265                          * We have no more space and have something to offer,
1266                          * wake up select/poll.
1267                          */
1268                         pipeselwakeup(wpipe);
1269
1270                         wpipe->pipe_state |= PIPE_WANTW;
1271                         pipeunlock(wpipe);
1272                         error = msleep(wpipe, PIPE_MTX(rpipe),
1273                             PRIBIO | PCATCH, "pipewr", 0);
1274                         if (error != 0)
1275                                 break;
1276                 }
1277         }
1278
1279         pipelock(wpipe, 0);
1280         --wpipe->pipe_busy;
1281
1282         if ((wpipe->pipe_busy == 0) && (wpipe->pipe_state & PIPE_WANT)) {
1283                 wpipe->pipe_state &= ~(PIPE_WANT | PIPE_WANTR);
1284                 wakeup(wpipe);
1285         } else if (wpipe->pipe_buffer.cnt > 0) {
1286                 /*
1287                  * If we have put any characters in the buffer, we wake up
1288                  * the reader.
1289                  */
1290                 if (wpipe->pipe_state & PIPE_WANTR) {
1291                         wpipe->pipe_state &= ~PIPE_WANTR;
1292                         wakeup(wpipe);
1293                 }
1294         }
1295
1296         /*
1297          * Don't return EPIPE if any byte was written.
1298          * EINTR and other interrupts are handled by generic I/O layer.
1299          * Do not pretend that I/O succeeded for obvious user error
1300          * like EFAULT.
1301          */
1302         if (uio->uio_resid != orig_resid && error == EPIPE)
1303                 error = 0;
1304
1305         if (error == 0)
1306                 vfs_timestamp(&wpipe->pipe_mtime);
1307
1308         /*
1309          * We have something to offer,
1310          * wake up select/poll.
1311          */
1312         if (wpipe->pipe_buffer.cnt)
1313                 pipeselwakeup(wpipe);
1314
1315         pipeunlock(wpipe);
1316         PIPE_UNLOCK(rpipe);
1317         return (error);
1318 }
1319
1320 /* ARGSUSED */
1321 static int
1322 pipe_truncate(fp, length, active_cred, td)
1323         struct file *fp;
1324         off_t length;
1325         struct ucred *active_cred;
1326         struct thread *td;
1327 {
1328         struct pipe *cpipe;
1329         int error;
1330
1331         cpipe = fp->f_data;
1332         if (cpipe->pipe_state & PIPE_NAMED)
1333                 error = vnops.fo_truncate(fp, length, active_cred, td);
1334         else
1335                 error = invfo_truncate(fp, length, active_cred, td);
1336         return (error);
1337 }
1338
1339 /*
1340  * we implement a very minimal set of ioctls for compatibility with sockets.
1341  */
1342 static int
1343 pipe_ioctl(fp, cmd, data, active_cred, td)
1344         struct file *fp;
1345         u_long cmd;
1346         void *data;
1347         struct ucred *active_cred;
1348         struct thread *td;
1349 {
1350         struct pipe *mpipe = fp->f_data;
1351         int error;
1352
1353         PIPE_LOCK(mpipe);
1354
1355 #ifdef MAC
1356         error = mac_pipe_check_ioctl(active_cred, mpipe->pipe_pair, cmd, data);
1357         if (error) {
1358                 PIPE_UNLOCK(mpipe);
1359                 return (error);
1360         }
1361 #endif
1362
1363         error = 0;
1364         switch (cmd) {
1365
1366         case FIONBIO:
1367                 break;
1368
1369         case FIOASYNC:
1370                 if (*(int *)data) {
1371                         mpipe->pipe_state |= PIPE_ASYNC;
1372                 } else {
1373                         mpipe->pipe_state &= ~PIPE_ASYNC;
1374                 }
1375                 break;
1376
1377         case FIONREAD:
1378                 if (!(fp->f_flag & FREAD)) {
1379                         *(int *)data = 0;
1380                         PIPE_UNLOCK(mpipe);
1381                         return (0);
1382                 }
1383                 if (mpipe->pipe_state & PIPE_DIRECTW)
1384                         *(int *)data = mpipe->pipe_map.cnt;
1385                 else
1386                         *(int *)data = mpipe->pipe_buffer.cnt;
1387                 break;
1388
1389         case FIOSETOWN:
1390                 PIPE_UNLOCK(mpipe);
1391                 error = fsetown(*(int *)data, &mpipe->pipe_sigio);
1392                 goto out_unlocked;
1393
1394         case FIOGETOWN:
1395                 *(int *)data = fgetown(&mpipe->pipe_sigio);
1396                 break;
1397
1398         /* This is deprecated, FIOSETOWN should be used instead. */
1399         case TIOCSPGRP:
1400                 PIPE_UNLOCK(mpipe);
1401                 error = fsetown(-(*(int *)data), &mpipe->pipe_sigio);
1402                 goto out_unlocked;
1403
1404         /* This is deprecated, FIOGETOWN should be used instead. */
1405         case TIOCGPGRP:
1406                 *(int *)data = -fgetown(&mpipe->pipe_sigio);
1407                 break;
1408
1409         default:
1410                 error = ENOTTY;
1411                 break;
1412         }
1413         PIPE_UNLOCK(mpipe);
1414 out_unlocked:
1415         return (error);
1416 }
1417
1418 static int
1419 pipe_poll(fp, events, active_cred, td)
1420         struct file *fp;
1421         int events;
1422         struct ucred *active_cred;
1423         struct thread *td;
1424 {
1425         struct pipe *rpipe;
1426         struct pipe *wpipe;
1427         int levents, revents;
1428 #ifdef MAC
1429         int error;
1430 #endif
1431
1432         revents = 0;
1433         rpipe = fp->f_data;
1434         wpipe = PIPE_PEER(rpipe);
1435         PIPE_LOCK(rpipe);
1436 #ifdef MAC
1437         error = mac_pipe_check_poll(active_cred, rpipe->pipe_pair);
1438         if (error)
1439                 goto locked_error;
1440 #endif
1441         if (fp->f_flag & FREAD && events & (POLLIN | POLLRDNORM))
1442                 if ((rpipe->pipe_state & PIPE_DIRECTW) ||
1443                     (rpipe->pipe_buffer.cnt > 0))
1444                         revents |= events & (POLLIN | POLLRDNORM);
1445
1446         if (fp->f_flag & FWRITE && events & (POLLOUT | POLLWRNORM))
1447                 if (wpipe->pipe_present != PIPE_ACTIVE ||
1448                     (wpipe->pipe_state & PIPE_EOF) ||
1449                     (((wpipe->pipe_state & PIPE_DIRECTW) == 0) &&
1450                      ((wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) >= PIPE_BUF ||
1451                          wpipe->pipe_buffer.size == 0)))
1452                         revents |= events & (POLLOUT | POLLWRNORM);
1453
1454         levents = events &
1455             (POLLIN | POLLINIGNEOF | POLLPRI | POLLRDNORM | POLLRDBAND);
1456         if (rpipe->pipe_state & PIPE_NAMED && fp->f_flag & FREAD && levents &&
1457             fp->f_seqcount == rpipe->pipe_wgen)
1458                 events |= POLLINIGNEOF;
1459
1460         if ((events & POLLINIGNEOF) == 0) {
1461                 if (rpipe->pipe_state & PIPE_EOF) {
1462                         revents |= (events & (POLLIN | POLLRDNORM));
1463                         if (wpipe->pipe_present != PIPE_ACTIVE ||
1464                             (wpipe->pipe_state & PIPE_EOF))
1465                                 revents |= POLLHUP;
1466                 }
1467         }
1468
1469         if (revents == 0) {
1470                 if (fp->f_flag & FREAD && events & (POLLIN | POLLRDNORM)) {
1471                         selrecord(td, &rpipe->pipe_sel);
1472                         if (SEL_WAITING(&rpipe->pipe_sel))
1473                                 rpipe->pipe_state |= PIPE_SEL;
1474                 }
1475
1476                 if (fp->f_flag & FWRITE && events & (POLLOUT | POLLWRNORM)) {
1477                         selrecord(td, &wpipe->pipe_sel);
1478                         if (SEL_WAITING(&wpipe->pipe_sel))
1479                                 wpipe->pipe_state |= PIPE_SEL;
1480                 }
1481         }
1482 #ifdef MAC
1483 locked_error:
1484 #endif
1485         PIPE_UNLOCK(rpipe);
1486
1487         return (revents);
1488 }
1489
1490 /*
1491  * We shouldn't need locks here as we're doing a read and this should
1492  * be a natural race.
1493  */
1494 static int
1495 pipe_stat(fp, ub, active_cred, td)
1496         struct file *fp;
1497         struct stat *ub;
1498         struct ucred *active_cred;
1499         struct thread *td;
1500 {
1501         struct pipe *pipe;
1502         int new_unr;
1503 #ifdef MAC
1504         int error;
1505 #endif
1506
1507         pipe = fp->f_data;
1508         PIPE_LOCK(pipe);
1509 #ifdef MAC
1510         error = mac_pipe_check_stat(active_cred, pipe->pipe_pair);
1511         if (error) {
1512                 PIPE_UNLOCK(pipe);
1513                 return (error);
1514         }
1515 #endif
1516
1517         /* For named pipes ask the underlying filesystem. */
1518         if (pipe->pipe_state & PIPE_NAMED) {
1519                 PIPE_UNLOCK(pipe);
1520                 return (vnops.fo_stat(fp, ub, active_cred, td));
1521         }
1522
1523         /*
1524          * Lazily allocate an inode number for the pipe.  Most pipe
1525          * users do not call fstat(2) on the pipe, which means that
1526          * postponing the inode allocation until it is must be
1527          * returned to userland is useful.  If alloc_unr failed,
1528          * assign st_ino zero instead of returning an error.
1529          * Special pipe_ino values:
1530          *  -1 - not yet initialized;
1531          *  0  - alloc_unr failed, return 0 as st_ino forever.
1532          */
1533         if (pipe->pipe_ino == (ino_t)-1) {
1534                 new_unr = alloc_unr(pipeino_unr);
1535                 if (new_unr != -1)
1536                         pipe->pipe_ino = new_unr;
1537                 else
1538                         pipe->pipe_ino = 0;
1539         }
1540         PIPE_UNLOCK(pipe);
1541
1542         bzero(ub, sizeof(*ub));
1543         ub->st_mode = S_IFIFO;
1544         ub->st_blksize = PAGE_SIZE;
1545         if (pipe->pipe_state & PIPE_DIRECTW)
1546                 ub->st_size = pipe->pipe_map.cnt;
1547         else
1548                 ub->st_size = pipe->pipe_buffer.cnt;
1549         ub->st_blocks = howmany(ub->st_size, ub->st_blksize);
1550         ub->st_atim = pipe->pipe_atime;
1551         ub->st_mtim = pipe->pipe_mtime;
1552         ub->st_ctim = pipe->pipe_ctime;
1553         ub->st_uid = fp->f_cred->cr_uid;
1554         ub->st_gid = fp->f_cred->cr_gid;
1555         ub->st_dev = pipedev_ino;
1556         ub->st_ino = pipe->pipe_ino;
1557         /*
1558          * Left as 0: st_nlink, st_rdev, st_flags, st_gen.
1559          */
1560         return (0);
1561 }
1562
1563 /* ARGSUSED */
1564 static int
1565 pipe_close(fp, td)
1566         struct file *fp;
1567         struct thread *td;
1568 {
1569
1570         if (fp->f_vnode != NULL)
1571                 return vnops.fo_close(fp, td);
1572         fp->f_ops = &badfileops;
1573         pipe_dtor(fp->f_data);
1574         fp->f_data = NULL;
1575         return (0);
1576 }
1577
1578 static int
1579 pipe_chmod(struct file *fp, mode_t mode, struct ucred *active_cred, struct thread *td)
1580 {
1581         struct pipe *cpipe;
1582         int error;
1583
1584         cpipe = fp->f_data;
1585         if (cpipe->pipe_state & PIPE_NAMED)
1586                 error = vn_chmod(fp, mode, active_cred, td);
1587         else
1588                 error = invfo_chmod(fp, mode, active_cred, td);
1589         return (error);
1590 }
1591
1592 static int
1593 pipe_chown(fp, uid, gid, active_cred, td)
1594         struct file *fp;
1595         uid_t uid;
1596         gid_t gid;
1597         struct ucred *active_cred;
1598         struct thread *td;
1599 {
1600         struct pipe *cpipe;
1601         int error;
1602
1603         cpipe = fp->f_data;
1604         if (cpipe->pipe_state & PIPE_NAMED)
1605                 error = vn_chown(fp, uid, gid, active_cred, td);
1606         else
1607                 error = invfo_chown(fp, uid, gid, active_cred, td);
1608         return (error);
1609 }
1610
1611 static int
1612 pipe_fill_kinfo(struct file *fp, struct kinfo_file *kif, struct filedesc *fdp)
1613 {
1614         struct pipe *pi;
1615
1616         if (fp->f_type == DTYPE_FIFO)
1617                 return (vn_fill_kinfo(fp, kif, fdp));
1618         kif->kf_type = KF_TYPE_PIPE;
1619         pi = fp->f_data;
1620         kif->kf_un.kf_pipe.kf_pipe_addr = (uintptr_t)pi;
1621         kif->kf_un.kf_pipe.kf_pipe_peer = (uintptr_t)pi->pipe_peer;
1622         kif->kf_un.kf_pipe.kf_pipe_buffer_cnt = pi->pipe_buffer.cnt;
1623         return (0);
1624 }
1625
1626 static void
1627 pipe_free_kmem(cpipe)
1628         struct pipe *cpipe;
1629 {
1630
1631         KASSERT(!mtx_owned(PIPE_MTX(cpipe)),
1632             ("pipe_free_kmem: pipe mutex locked"));
1633
1634         if (cpipe->pipe_buffer.buffer != NULL) {
1635                 atomic_subtract_long(&amountpipekva, cpipe->pipe_buffer.size);
1636                 vm_map_remove(pipe_map,
1637                     (vm_offset_t)cpipe->pipe_buffer.buffer,
1638                     (vm_offset_t)cpipe->pipe_buffer.buffer + cpipe->pipe_buffer.size);
1639                 cpipe->pipe_buffer.buffer = NULL;
1640         }
1641 #ifndef PIPE_NODIRECT
1642         {
1643                 cpipe->pipe_map.cnt = 0;
1644                 cpipe->pipe_map.pos = 0;
1645                 cpipe->pipe_map.npages = 0;
1646         }
1647 #endif
1648 }
1649
1650 /*
1651  * shutdown the pipe
1652  */
1653 static void
1654 pipeclose(cpipe)
1655         struct pipe *cpipe;
1656 {
1657         struct pipepair *pp;
1658         struct pipe *ppipe;
1659
1660         KASSERT(cpipe != NULL, ("pipeclose: cpipe == NULL"));
1661
1662         PIPE_LOCK(cpipe);
1663         pipelock(cpipe, 0);
1664         pp = cpipe->pipe_pair;
1665
1666         pipeselwakeup(cpipe);
1667
1668         /*
1669          * If the other side is blocked, wake it up saying that
1670          * we want to close it down.
1671          */
1672         cpipe->pipe_state |= PIPE_EOF;
1673         while (cpipe->pipe_busy) {
1674                 wakeup(cpipe);
1675                 cpipe->pipe_state |= PIPE_WANT;
1676                 pipeunlock(cpipe);
1677                 msleep(cpipe, PIPE_MTX(cpipe), PRIBIO, "pipecl", 0);
1678                 pipelock(cpipe, 0);
1679         }
1680
1681
1682         /*
1683          * Disconnect from peer, if any.
1684          */
1685         ppipe = cpipe->pipe_peer;
1686         if (ppipe->pipe_present == PIPE_ACTIVE) {
1687                 pipeselwakeup(ppipe);
1688
1689                 ppipe->pipe_state |= PIPE_EOF;
1690                 wakeup(ppipe);
1691                 KNOTE_LOCKED(&ppipe->pipe_sel.si_note, 0);
1692         }
1693
1694         /*
1695          * Mark this endpoint as free.  Release kmem resources.  We
1696          * don't mark this endpoint as unused until we've finished
1697          * doing that, or the pipe might disappear out from under
1698          * us.
1699          */
1700         PIPE_UNLOCK(cpipe);
1701         pipe_free_kmem(cpipe);
1702         PIPE_LOCK(cpipe);
1703         cpipe->pipe_present = PIPE_CLOSING;
1704         pipeunlock(cpipe);
1705
1706         /*
1707          * knlist_clear() may sleep dropping the PIPE_MTX. Set the
1708          * PIPE_FINALIZED, that allows other end to free the
1709          * pipe_pair, only after the knotes are completely dismantled.
1710          */
1711         knlist_clear(&cpipe->pipe_sel.si_note, 1);
1712         cpipe->pipe_present = PIPE_FINALIZED;
1713         seldrain(&cpipe->pipe_sel);
1714         knlist_destroy(&cpipe->pipe_sel.si_note);
1715
1716         /*
1717          * If both endpoints are now closed, release the memory for the
1718          * pipe pair.  If not, unlock.
1719          */
1720         if (ppipe->pipe_present == PIPE_FINALIZED) {
1721                 PIPE_UNLOCK(cpipe);
1722 #ifdef MAC
1723                 mac_pipe_destroy(pp);
1724 #endif
1725                 uma_zfree(pipe_zone, cpipe->pipe_pair);
1726         } else
1727                 PIPE_UNLOCK(cpipe);
1728 }
1729
1730 /*ARGSUSED*/
1731 static int
1732 pipe_kqfilter(struct file *fp, struct knote *kn)
1733 {
1734         struct pipe *cpipe;
1735
1736         /*
1737          * If a filter is requested that is not supported by this file
1738          * descriptor, don't return an error, but also don't ever generate an
1739          * event.
1740          */
1741         if ((kn->kn_filter == EVFILT_READ) && !(fp->f_flag & FREAD)) {
1742                 kn->kn_fop = &pipe_nfiltops;
1743                 return (0);
1744         }
1745         if ((kn->kn_filter == EVFILT_WRITE) && !(fp->f_flag & FWRITE)) {
1746                 kn->kn_fop = &pipe_nfiltops;
1747                 return (0);
1748         }
1749         cpipe = fp->f_data;
1750         PIPE_LOCK(cpipe);
1751         switch (kn->kn_filter) {
1752         case EVFILT_READ:
1753                 kn->kn_fop = &pipe_rfiltops;
1754                 break;
1755         case EVFILT_WRITE:
1756                 kn->kn_fop = &pipe_wfiltops;
1757                 if (cpipe->pipe_peer->pipe_present != PIPE_ACTIVE) {
1758                         /* other end of pipe has been closed */
1759                         PIPE_UNLOCK(cpipe);
1760                         return (EPIPE);
1761                 }
1762                 cpipe = PIPE_PEER(cpipe);
1763                 break;
1764         default:
1765                 PIPE_UNLOCK(cpipe);
1766                 return (EINVAL);
1767         }
1768
1769         kn->kn_hook = cpipe;
1770         knlist_add(&cpipe->pipe_sel.si_note, kn, 1);
1771         PIPE_UNLOCK(cpipe);
1772         return (0);
1773 }
1774
1775 static void
1776 filt_pipedetach(struct knote *kn)
1777 {
1778         struct pipe *cpipe = kn->kn_hook;
1779
1780         PIPE_LOCK(cpipe);
1781         knlist_remove(&cpipe->pipe_sel.si_note, kn, 1);
1782         PIPE_UNLOCK(cpipe);
1783 }
1784
1785 /*ARGSUSED*/
1786 static int
1787 filt_piperead(struct knote *kn, long hint)
1788 {
1789         struct pipe *rpipe = kn->kn_hook;
1790         struct pipe *wpipe = rpipe->pipe_peer;
1791         int ret;
1792
1793         PIPE_LOCK_ASSERT(rpipe, MA_OWNED);
1794         kn->kn_data = rpipe->pipe_buffer.cnt;
1795         if ((kn->kn_data == 0) && (rpipe->pipe_state & PIPE_DIRECTW))
1796                 kn->kn_data = rpipe->pipe_map.cnt;
1797
1798         if ((rpipe->pipe_state & PIPE_EOF) ||
1799             wpipe->pipe_present != PIPE_ACTIVE ||
1800             (wpipe->pipe_state & PIPE_EOF)) {
1801                 kn->kn_flags |= EV_EOF;
1802                 return (1);
1803         }
1804         ret = kn->kn_data > 0;
1805         return ret;
1806 }
1807
1808 /*ARGSUSED*/
1809 static int
1810 filt_pipewrite(struct knote *kn, long hint)
1811 {
1812         struct pipe *wpipe;
1813
1814         wpipe = kn->kn_hook;
1815         PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
1816         if (wpipe->pipe_present != PIPE_ACTIVE ||
1817             (wpipe->pipe_state & PIPE_EOF)) {
1818                 kn->kn_data = 0;
1819                 kn->kn_flags |= EV_EOF;
1820                 return (1);
1821         }
1822         kn->kn_data = (wpipe->pipe_buffer.size > 0) ?
1823             (wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) : PIPE_BUF;
1824         if (wpipe->pipe_state & PIPE_DIRECTW)
1825                 kn->kn_data = 0;
1826
1827         return (kn->kn_data >= PIPE_BUF);
1828 }
1829
1830 static void
1831 filt_pipedetach_notsup(struct knote *kn)
1832 {
1833
1834 }
1835
1836 static int
1837 filt_pipenotsup(struct knote *kn, long hint)
1838 {
1839
1840         return (0);
1841 }